Sunday 5 February 2012

AVM not seen after bleed

38 y o male, a known case of left parietal AVM.
DSA dated 21-11-11 show an obvious nidus of left parietal AVM with left ACA as feeder and ultimately draining into superior Sagittal sinus.
After a month readmitted for a recent onset right sided weakness.
On admission MRI shows a focal left parietal para sagittal bleed with low signal intensity hemosiderin staining on T2*GRE, T1 bright Meth Hb, a sub acute stage blood degradation product. It’s a secondary intra cranial haemorrhage as site was atypical for bleed and cause is ruptured AVM as per previous MRI and DSA details.
MRI Brain is immediately followed by Non contrast 3D TOF MR Brain Angiography revealed no obvious AVM. Even strange is that DSA also was normal.

An arteriovenous malformation is a tangled cluster of vessels, in which arteries connect directly to veins without any intervening capillary bed.

When AVM Bleeds it may not be obvious on immediate follow up MRA or even on DSA. The reason may be mass effect of hematoma and perilesional odema over the nidus or it may have gone out of cerebral circulation due to rupture of feeder itself.
In such cases follow up MRI studies may be needed to rule out an underlying cause of bleed like AVM or any other vascular malformation which may not be obvious on a single MRI study performed immediately after bleed.

1 comment:

Gustavo said...

In a case of unknow AVM presentig with a onset of hemorrhage, that we only see hematoma and aodema, in how many time we have to wait to do a new study with another conventional MRI, or ANGIO-RM or TC, or even a DSA if necessary, to swou us the AVM? Another question: The AVM can desapear?